


Hello, From the Underground

by woomy_veemo



Series: The HeroTale Series [1]
Category: Undertale (Video Game), 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia
Genre: F/F, F/M, He's also very serious... in the first couple(?) of chapter(s?), Honestly I wasn't planning on having the MHA characters show up but, I had too I'm sorry :'), I'm very indecisive- sorry :'), Older Canon MHA Characters, One-Sided Attraction, Other Additional Tags to Be Added, Past Sans/Alphys, Rating May Change, Reader Is Not Chara, Reader Is Not Frisk, Reader has a quirk, Sans is desperate to get tf out, Slow Burn, Technology is advanced Underground, Undertale x MHA, crossover AU, i'll update tags as i write, the / means romantic and the & means friendship
Language: English
Status: In-Progress
Published: 2018-04-14
Updated: 2018-07-12
Packaged: 2019-04-22 16:52:48
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 2
Words: 2,009
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/14313078
Author URL: https://archiveofourown.org/users/woomy_veemo/pseuds/woomy_veemo
Summary: [ Undertale x My Hero Academia ][ Sans x F. Reader x Izuku Midoriya ]





	1. ⎣❖ cн. 001 // connecтed ❖⎤

**Author's Note:**

> **⚠ ATTENTION READERS!! PLEASE READ THIS NOTE TO CONTINUE, THANK YOU. ⚠**   
>  _Before I go into anything really important about this story-, I want to thank you for reading my self-indulgent fan-fiction! I hope you enjoy reading this! :D_
> 
> ⟹ Since this is a crossover AU, Sans might have a different personality from canon since there are no resets here. ( sorry to disappoint;; )
> 
> ⟹ Please keep in mind that this is a slow burn Sans x Reader, it'll take awhile for the mutual pining to start.
> 
> ⟹ Reader is female and 23 years old. Her colors and name is up to you but I'll have a body type, hairstyle and height already set in place for her.
> 
> ⟹ She does has a quirk. You have to read the actual chapters to know what it is though~
> 
> ⟹ Expect references. A lot of them.
> 
> ⟹ Reminder- Sans and Gaster are not related in this fic/AU.
> 
> ==============
> 
> Large piles of useful human trash have stopped falling from the surface. Then humans stopped falling. The Underground was a mess, how will they escape now? It has been a mess for months.
> 
> Months turned into years...    
> 
>  **[Year 19XX]**  
>  Royal scientist Dr. W.D. Gaster was having none of this nonsense! There was still salvageable human equipment! He could attempt to fuse magic from the barrier with said equipment to make highly advanced technology! And so fueled with false determination, he worked on what was going to change the Underground for the best. What he didn't anticipate, was the powerful impact of his magical project was going to change humanity as well.  
>  
> 
> **[Interlude a year later - on the surface...]**  
>  A child was born that radiated light... and so, quirks came to life.  
>  
> 
> **[Year 20XX]**  
>  After many years of hard work and collecting rare pieces of new human technology that managed to fall Underground- Gaster managed to invent his second most anticipated creation- the SOUL Searcher. The SOUL Searcher is a tech-magi machine that should be strong enough to be able to connect to someone from the surface but... it failed many times. This is when he finally decided that he needed some help from other brilliant scientists and so, he searches.
> 
>  
> 
> _This is where Sans and Alphys come and help better the project._

_B e e p... B e e p... B e e p..._

_**DING** _

A monotone robotic voice is heard through the speakers. " **SURFACE NETWORK DATA FOUND. PERMISSION TO ACCESS IT?** " Taking a deep breath, the royal scientist types out a response- his assistant fidgeting in anticipation.

"permission granted"

" **UNDERSTOOD. ACCESSING INFORMATION. DATA FILES. SURFACE WEB.--** "

Both scientists stare at the screen in hope as the list goes on and on. Is this it? Will they finally be able to communicate with a human from the surface? Or multiple if they get lucky? Will they be willing to help them break the barrier without blood being shed? Or will they...?

"H-Hey Sans... D-Do you really think this is going to w-work...?"

Sans raises a bone-brow at her.

"well... why wouldn't it? this may be a test run but you never know. we might just be successful this time--"

**_DING_ **

" **ACCESS GRANTED. CONNECTION TO SURFACE SERVER USA-MC081897 IS NOW ONLINE.** "

Sans and Alphys stare at the screen in shock as the screen changes to what looks like... some kind of chatroom? It looks kind of... weird, but it must be trustworthy... right? Or was there an error in the program? It wouldn't be the first time their tech magic has failed. But it read non-underground frequencies also this isn't an underground server and website so it has to be...

_**~ bing ~**_

**===============**

**sweetchi:**  Um... Hello?

 **sweetchi:** Sorry, I'm kinda new to this so. uhhh? ;;

_sweetchi is typing..._

**===============**

Alphys then grabs Sans by his shoulders and starts shaking him back and forth. "O-o-o-oh my god!!! Sans!!! You were r-r-right!" Sans snaps out of his trance and grabs Alphys' hands. "please stop."

She pulls her hands away in embarrassment.

"S-Sorry!"

He shrugs, lightly blushing and looks back at the large screen.

" it's fine... so- looks like we have to fill out this info to chat? so. who's gonna reply? you or me?"

Alphys stares at the screen uncomfortably. "Y...You should do it." Sans raises a bone-brow at her reaction. "...alright then." He types in some fake info, his username for literally everything and enters the chat.

"I'm... uh... I'm going to go tell the others alright? Be right back!" Alphys scurries off. 

"...'kay i guess i'm doing this alone..." He takes a deep breath.

_ 'okay sans, stay cool, be cool and don't say anything to scare the human away. don't screw this up... okay so, looks like there's a profile for them? better skim through it... but first.' _

**===============**

**SpoopySkeles:**  hey? it's fine i'm pretty new to this too. ;;

**===============**

_ 'that seems pretty natural, right? ... i uh, i hope so...' _

**~bing~**

****===============** **

**sweetchi:**  Oh, so you finally responded stranger~

 **sweetchi:** Thank goodness! For a second there I thought I screwed up already... haha n v n;

 **sweetchi:**  I like your username btw! You into the whole skeleton aesthetic? c:

 **SpoopySkeles:**  heh thanks.

 **SpoopySkeles:** yeah i guess? so what's the story behind _your_ username??

 **sweetchi:**  Oh- It's actually from a visual novel game that I really like. One of the characters is named "Shuichi Saihara" and is nicknamed "Sweetchi" by another character in a special event so...

 **SpoopySkeles:**  ...so. what's the vn called?

 **sweetchi:** Danganronpa V3: Killing Harmony. Have you heard of it?

 **SpoopySkeles:**  nope.

 **sweetchi:**  Oh, I had a feeling that you didn't; There are 3 main games and a couple of spin-offs. 

 **sweetchi:** I could look for a let's play on YouTube if you want?

 **SpoopySkeles:** yeah sure, why not?

_sweetchi is typing..._

**===============**

_this is a good opportunity to see if it'll let us access other sites besides this one. also to see what kind of games do humans like- is it something similar to us or is it something completely different? probably the same considering...'_

_**~ bing ~** _

===============

**sweetchi: [[nicoB](https://www.youtube.com/user/NicoB7700/playlists?shelf_id=14&view=50&sort=dd)]**

**sweetchi:** Um, there's not a lot of lets plays/reactions to the VN but this is one of my favorite YouTubers that's played all the games.

 **SpoopySkeles:**  it's alright? brb

 **sweetchi:**  Alright... n v n;

**===============**

He clicks on the first link, it sends him straight to a website called "YouTube". It... worked. It worked!!

There are multiple playlists of all the games, even reactions to... the anime? It has an anime? Interesting. Alphys would love this... he saves the page's IP address and closes it, finding an opportunity to look into the human he was speaking to. Once he clicks on their... no, _her_ , profile- He takes note that the human is, in fact, a female - and an attractive one at that ( ~~'~~ _ ~~what's up with that hair though? is it a camera filter? no, Sans you're getting out track here'~~  _)- he suddenly feels a lot more self-conscious than before. He doesn't understand why-  _she's just a human_. Snapping out of it he goes back to reading her profile.

' _[Y/N] [L/N]... huh. Sounds nice._ '

Once he's finished reading her profile, he goes back to "YouTube" just in case she asks him anything about the games. Sans clicks on the one she mentioned- "[DRV3](https://www.youtube.com/watch?v=uynHAtX-F8I&list=PL5bkYBlFL9xdERZrmVrHANWy9o12MLoHG)" 

_'...this game. looks kinda... fucked up. humans are into this? she's into this?... i shouldn't judge really...'_

**===============**

**SpoopySkeles:** wellthat was... interesting.

 **sweetchi:** aaaaa yeah. It's a bit... messed up. I know;;;

 **sweetchi:** but it's a good game I swear!! The mystery, art and characters are awesome!!

 **SpoopySkeles:** wow someone's passionate lol.

 **sweetchi:** ehehe;; yeah I love that game.~ ; v ;

 **sweetchi:** Sorry I've just been talking about myself- so uh... tell me about yourself!

 **SpoopySkeles:** ah, i'm not that interesting haha;

 **sweetchi:** so... no hobbies?

 **SpoopySkeles:** i mean... i like to build things and study about space and all that.

 **sweetchi:** ooo space!! So you're studying astronomy?

 **SpoopySkeles:** yeah! space is so cool.

 **sweetchi:** Can't disagree~ the stars are so beautiful! And knowing there's millions and millions of them out there is mind-blowing~

 **SpoopySkeles:** haha yeah.

 **sweetchi:** oh yeah! i almost forgot to mention but um- when we started chatting, was your computer/laptop/phone acting weird?? 

 **SpoopySkeles:** uhhh... no? is there something wrong?

 **sweetchi:** ah... nah, it's fine! must be my laptop glitching out again;; just wanted to make sure if this site wasn't buggy or something.

 **SpoopySkeles:** you should get your laptop checked... just in case you know?

**===============**

He can't lose his only connection to the surface after all... his co-workers and himself have worked on this project for so many years! He's so close to--

**~bing~**

**===============**

**sweetchi:** I'll think about it c: !

 **sweetchi:** If it keeps acting weird I'll go first thing tomorrow once I'm done with my hero work! ^ ^

 **SpoopySkeles:**...hero work??

 **sweetchi:** Yep! I'm not that well-known around here but I try my best help people. //sigh

 **sweetchi:** Makes me wish I had of gone to that famous hero school in Japan during my high-school years... but my Japanese was still pretty rusty so it would have been bad times for me haha;;

**===============**

Sans keeps staring the screen in pure confusion. _'heroes? ....like comic book heroes? what in the world-?'_

_Also, why did the phrase "bad times" make him feel... uneasy?_

**~ bing ~**

**===============**

**sweetchi:** oh uh... you're not... against heroes right? ^ ^;;

 **sweetchi:** ... Sans? You still there?

 **SpoopySkeles:** oh yeah! i was just... wow! you're a hero! that's so cool!

 **SpoopySkeles:** wait, isn't that suppose to be like a secret or something?

 **sweetchi:** Nah. Heroes don't have secret identities silly~

 **sweetchi:** oh shoot, duty ca .lls! um... talk to you later?

 **SpoopySkeles:** yeah, sounds good. (:

 **sweetchi:** ^ ^ well then, later!

 **SpoopySkeles:** later.

_sweetchi is offline_

**===============**

Sans is still really confused about the whole hero thing.

_'did humans regain magic? or was there an outbreak of some weird chemical that gave them powers? did she mean it metaphorically? or was she... joking?'_

He doubted those two last thoughts from how serious she sounded about going to "that famous hero school in Japan". Although... there's also a possibility she was lying about herself to him the entire time. He lowers his skull and sighs in frustration.

" _ugggh_ , too much was thrown at me at once! i can't think clearly like this-"

"Sans?"

He squeals in fright then turns around with an embarrassed bright blue blush, scowling.

"DON'T do that!"

Alphys waves her hands and tries not to laugh at the sound Sans made.

"S-Sorry! Pppfffft-"

Sans rolls his eye-lights. 

"... ** _anyways_** , i'm done talking to the human for today. found some really interesting details about the surface from her if you're... _wait_ where's everyone else? i thought you were going to bring them?"

She stops giggling and looks away in a slight panic.

"I uh... well actually... they all... left already..." Sans blankly stares at Alphys.

**_"w h a t ?"_ **

She starts fidgeting around nervously- looking at anywhere except at Sans.

"W-Well... you were taking longer than w-we thought you would so... we d-didn't want to interrupt you o-or anything... B-BUT! We can tell t-them tomor..row? Sans? I-Is there something wrong?"

He shakes is head in frustration.

"i just can't believe they _left_ when _they were **supposed** to be keeping an eye on the main core of **the SOUL searcher**."_  

Again, he takes a deep breath to calm down.

"...whatever, since i'm done _here_ i'll check on it myself."

"Oh no you don't need to! I-I already checked the stats of the human you talked to!"

Sans rises a brow, he almost forgot about  _that_. Maybe that's what caused her laptop to glitch out?

"oh? so. where are the stats?"

Alphys hands him over a folder he just noticed she had with her. "Here."

He flips through the notes- checking to see if the human was capable of being able to help them get out of this hellhole. His eye sockets widen as he notices some odd numbers in the stats.

_ ' **damn**. that's an abnormal amount of water for an average human.... she wasn't kidding then, humans **have** changed.' _

Sans closes the folder and nods to himself.

 _'this... this is a good thing right? more, possibly stronger, humans can help her break the barrier without the need of human SOULs anymore.'_ **Then it dawns on him.** _'no more innocent lives need to be taken!! this **is** great!!'_

Sans turns to Alphys with a huge grin on his face.

**_"alph! i-i can't believe i'm saying this but... we need to get mettaton, right here. right now. i've got some good news to announce to everyone in the underground!"_ **

* * *

_Jumping the gun a bit- don'tcha think Sans? ;;; Reader hasn't even agreed to anything yet... ;;;_

Again sorry for any grammar errors or if anything doesn't make any sense :')!

Also, did you catch onto Read's quirk? Comment on what you think it is~ Hope you enjoyed :D

<b>(edited but not beta-read)</b>


	2. . a/n // story key .

**Summary for the Chapter:**

> an alternative for this fic!!

this will now be a "choose your own path/adventure" fic!

[ the update may take a little while longer now. so, uh, i'm sorry? (': ]

 

your choices  _ **will**_  affect the way the story goes for you so now don't forget this okay?

(btw the selection/stats/layout will be identical to Detroit: Become Human

 

(i'll have a key here so you'll understand what i mean if you don't know what D:BH is or you haven't seen a gameplay or played the game.)

* * *

  **KEY**

_Each time you make your choice- this'll show up on your right-hand corner on the next chapter (aka the chapter of your choice)._

  * **|| (Character Name)⤴ \\\ = means the character's opinion of you increased.**
  * **|| (Character Name)⤴ **⤴** \\\ = means the character's opinion of you increased significantly.**
  * **|| (Character Name) \\\ = means the character's opinion of you is the same.**
  * **|| (Character Name)⤵ \\\ = means the character's opinion of you decreased.**
  * **|| (Character Name)⤵ **⤵** \\\ = means the character's opinion of you decreased significantly** **.**



_This'll show up next to the name of the character- showing how they feel about the Reader._

  * **[betrayed] = means you completely betrayed the character- this is irreversible unlike hostile or distrusted.**
  * **[distrusted] = a mix of hostile and betrayed, depends on what you did/chose- you can either recover from this or cannot.**
  * **[hostile] = means the character highly dislikes you.**
  * **[tense] = as stated**
  * **[neutral] = as stated**
  * **[trusted] = as stated.**



**(( the following is a picture since AO3 is acting stupid c':**

**Notes for the Chapter:**

> **UPDATE 02/06/2019:**
> 
> AO3 didn’t let me add the rest of what’s shown rip—
> 
> Anyways!! I decided there’s going to be TWO versions of this fic! I actually got mixed reactions for the “choose your own path” SO... I’m going to make that on a separate book and leave the first chapter of this one as is! ( Yes that means I’m FINALLY going to come back to this fic since I have a much better job now with reasonable hours :’) )


End file.
